| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Taurus |
| Right ascension | 03h 47m 29.1s |
| Declination | +24° 06' 18" |
| Apparent magnitude (V) | +2.85 |
| Distance | 440 ly (135 pc) |
| Spectral type | B7IIIe+A0V+A0V+F2V |
| Other designations | |
Alcyone (η Tau / η Tauri / Eta Tauri) is a star system in the constellation Taurus. It is the brightest star in the Pleiades open cluster, which is a young cluster, aged at less than 50 million years. Alcyone is approximately 400 light years from Earth. It is named after the mythological figure Alcyone, one of the mythological Pleiades.
Description
The primary component, Alcyone A, is a blue-white B-type giant with an apparent magnitude of +2.85 (absolute magnitude = -2.4), and a radius 5 times that of the Sun. It is an eclipsing binary, and the two components have a separation of 0.031 arcseconds, or about the distance from the Sun to Jupiter.
The binary star is orbited by three companions. Alcyone B and Alcyone C are both 8th magnitude white A-type dwarfs and are separated from A by 117 and 181 arcseconds respectively. Alcyone D is a yellow-white F-type dwarf, 191 arcseconds from the primary. It has an apparent magnitude of +8.7. Alcyone C is classified as a Delta Scuti type variable star and its brightness varies from magnitude +8.25 to +8.30 over 1.13 hours.
Alcyone A has a luminosity of 750 times that of the Sun and a temperature of almost 13,000 K. The spectral type of B7 IIIe indicates that it is an emission star. A high rotational velocity of some 215 km/s has created a disk of gases flung into orbit around the star from its equator.
It is known as 昴宿六 (the Sixth Star of the Hairy Head) in Chinese.
External links
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